This list contains 64 species and varieties of alien vascular plants considered to be invasive in the state of Delaware. These species are, or have extreme potential to be detrimental to natural systems, i.e., displace native vegetation and disrupt ecological processes. This list is based on personal knowledge, consultation with knowledgeable individuals, and the literature.

Species highlighted in bold are considered to be the most damaging to natural areas in the state. These species are usually shade tolerant, many have a perennial habit, many reproduce and spread primarily by seed and/or spread rapidly through vegetative means, many occur in a variety of habitat types, and many are currently widespread and abundant in the state or have high potential to become widespread.

The purpose of this list is not regulatory, it is to serve only as a reference, advising those who have an interest in alien plant species in Delaware.